The development of cleansing formulations for the face, the body and the hair, and in general body and hair hygiene products, presented in the form of shampoos, lotions, gels or liquid soaps requires the formation of foam during application to the part of the body to be cleansed. This concern is particularly important since, in the eyes of the consumer, the creation of foam constitutes one of the proofs of the cleansing efficacy of these formulations. In the development of cleansing formulations for body and hair hygiene, the volume of foam generated by the formulation, and also its stability and the sensory properties of said foam, constitute an important criterion for the commercial success of the products proposed to consumers. Thus, the search for formulations that generate a foam of good quality is also broadened to all washing products for the body, shower gels and bubble baths.
Several categories of surfactant are used for the preparation of formulations for cleansing purposes: cationic, anionic, amphoteric or nonionic surfactants.
Anionic surfactants, such as sulfated anionic surfactants or surfactants of the alkylcarboxylate family, constitute a class of surfactants that is frequently used on account of their good foaming properties. These surfactants are reputed for their good cleansing power, and may also produce an airy foam whose feel is not considered by consumers to be unpleasant. However, these surfactants have the drawback of being sensitive to the degree of water hardness and to the presence of greasy soiling, which consequently induces a reduction in the volume of foam initially generated by these formulations, but above all a reduction in the stability over time of this volume of foam.
To reduce the magnitude of these phenomena, without, however, eliminating them altogether, it is preferred to use alkyl ether sulfates rather than alkyl sulfates. Another solution, which again is only partially satisfactory, consists in using nonionic surfactants, such as alkylpolyglycosides, for instance decyl polyglucoside or capryl/caprylyl polyglucoside. On account of their nonionic structure, these surfactants are compatible with any other type of surfactant, of additive and of active agent with cosmetic properties, irrespective of their anionic, cationic or nonionic nature. They especially show excellent compatibility with the quaternary ammonium derivatives used either for their bactericidal properties, or for their hair-conditioning effect. Furthermore, alkylpolyglycosides are known for their excellent capacity to form an abundant, stable foam, independently of the pH of the formulation, which foam is insensitive to the degree of water hardness and to the presence of greasy soiling. However, alkylpolyglycosides produce a foam that has mediocre sensory characteristics, reflected by a coarse foam feel, which induces during the rinsing phase a grating effect that consumers find particularly unpleasant, both on the skin and on the hair.
To attempt to overcome these drawbacks, it is necessary either to use a small dose of alkylpolyglycosides in the cleansing formulations, or to combine the alkylpolyglycosides with feel modifiers, for instance water-soluble fatty phases such as silicone fatty phases or esters. Although such combinations make it possible to improve the sensory properties of the foam, they however have the consequence of very significantly reducing the volume of foam formed during use by the consumer, and, in certain cases, of impairing the foam stability over time.
The inventors have thus sought to develop a novel solution for improving the foaming properties of cosmetic, dermocosmetic, dermopharmaceutical or pharmaceutical formulations.